Expert systems are ubiquitous in the manufacturing environment. This is especially true in the semiconductor industry where wafer processing systems require constant monitoring to ensure adequate quality control to maintain acceptable product yields.
Building a knowledge base traditionally requires the services of a knowledge engineer working closely with line operators and support personnel to identify and classify problem-solving approaches. However, there sometimes is resistance to the idea of surrendering the decision-making process which takes place during the monitoring and adjusting of a process. Oftentimes, the expert (i.e. process engineer, line operator, etc.) is uncertain as to the knowledge engineer's formulation of the knowledge base and whether the expert's knowledge is being accurately transferred into the knowledge base. Once the information has been programmed by the knowledge engineer the expert has no control over the resulting knowledge base and adjustments require additional interaction with the knowledge engineer.
Various improvements have occurred during the evolution of knowledge-based systems. In U.S. Pat. No. 4,924,408, for example, a method is described for increasing the execution speed of a knowledge system by compiling the inference engine and the knowledge base into machine-level code. U.S. Pat. No. 4,935,876 a technique for managing knowledge databases as they increase in size due to the accumulation of knowledge. U.S. Pat. No. 5,548,714 discloses a graphically driven user interface wherein users who have no background in expert systems can construct an expert system.
What is needed is a technique for utilizing a knowledge-based system which increases accessibility to the knowledge base by the expert. It is further desirable that the knowledge base can be defined by the expert, absent the assistance of a knowledge engineer.